This paper is about how teachers read student writing in the context of criteria-based assessment as it currently operates in secondary schools in Queensland, Australia. Throughout, the term 'reading' is understood to encompass responding to students' writing and assessing it for grading purposes. In the paper, attention focuses on different types of knowledge that teachers have available to them, including what is referred to metaphorically as 'knowledge files'. Of special interest are the ways in which knowledge files can be accessed to open up (or close down) pathways for reading student writing produced for assessment. Also of interest is the interplay that occurs between stated assessment criteria, as supplied to students when they commence an assessable task, and other considerations that influence how teachers read and ascribe meaning and value to student papers.